IPv6 Access Control
Lists

Access lists
determine what traffic is blocked and what traffic is forwarded at device
interfaces and allow filtering of traffic based on source and destination
addresses, and inbound and outbound traffic to a specific interface. Standard
IPv6 ACL functionality was extended to support traffic filtering based on IPv6
option headers and optional, upper-layer protocol type information for finer
granularity of control. Standard IPv6 ACL functionality was extended to support
traffic filtering based on IPv6 option headers and optional, upper-layer
protocol type information for finer granularity of control.

This module describes
how to configure IPv6 traffic filtering and to control access to virtual
terminal lines.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Information About IPv6 Access Control Lists

Access Control Lists for IPv6
Traffic Filtering

The standard ACL
functionality in IPv6 is similar to standard ACLs in IPv4. Access lists
determine what traffic is blocked and what traffic is forwarded at device
interfaces and allow filtering based on source and destination addresses,
inbound and outbound to a specific interface. Each access list has an implicit
deny statement at the end. IPv6 ACLs are defined and their deny and permit
conditions are set using the
ipv6access-listcommand with the
deny and
permit keywords
in global configuration mode.

IPv6 extended ACLs
augments standard IPv6 ACL functionality to support traffic filtering based on
IPv6 option headers and optional, upper-layer protocol type information for
finer granularity of control (functionality similar to extended ACLs in IPv4).

IPv6 Packet Inspection

The following header fields are used for IPv6 inspection: traffic class, flow label, payload length, next header, hop limit, and source or destination IP address. For further information on and descriptions of the IPv6 header fields, see RFC 2474.

Access Class Filtering in
IPv6

Filtering incoming
and outgoing connections to and from the device based on an IPv6 ACL is
performed using the
ipv6access-class command in line configuration mode.
The
ipv6access-class command is similar to the
access-class
command, except the IPv6 ACLs are defined by a name. If the IPv6 ACL is applied
to inbound traffic, the source address in the ACL is matched against the
incoming connection source address and the destination address in the ACL is
matched against the local device address on the interface. If the IPv6 ACL is
applied to outbound traffic, the source address in the ACL is matched against
the local device address on the interface and the destination address in the
ACL is matched against the outgoing connection source address. We recommend
that identical restrictions are set on all the virtual terminal lines because a
user can attempt to connect to any of them.

How to Configure IPv6 Access Control Lists

Configuring IPv6 Traffic Filtering

Creating and Configuring an
IPv6 ACL for Traffic Filtering

Note

IPv6 ACLs on
the Cisco ASR 1000 platform do not contain implicit permit rules. The IPv6
neighbor discovery process uses the IPv6 network-layer service; therefore, to
enable IPv6 neighbor discovery, you must add IPv6 ACLs to allow IPv6 neighbor
discovery packets to be sent and received on an interface. In IPv4, the Address
Resolution Protocol (ARP), which is equivalent to the IPv6 neighbor discovery
process, uses a separate data-link-layer protocol; therefore, by default IPv4
ACLs implicitly allow ARP packets to be sent and received on an interface.

Technical Assistance

Description

Link

The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.